At present, Peer-to-Peer (P2P) communication has attracted significant attention in the computer industry. Different from the traditional Client/Server (C/S) mode, each device in a P2P network in the P2P communication mode is peer to each other, which means the each device can serve not only as a server providing data service to another device, but also as a client utilizing the data service provided by another device. No matter P2P communication or C/S communication, a secured traffic among different devices is always worthwhile to be addressed.